A vacuum cleaner draws in air by driving a motor-driven fan in a main body of a vacuum cleaner. The suction or vacuum created by the fan draw in dusts and contaminant-laden air from an external surface being cleaned.
Prior art vacuum cleaners generally use a dust bag and/or dust filter to collect dust, but recently, a cyclone dust collecting devices have been used to collect dust in a vacuum cleaner because they have an unlimited life span, are easy to empty and easy to clean.
Korean Utility Model Application No. 1993-4891 entitled ‘Vacuum cleaner having a cyclone’ and Korean Patent Application No. 1993-5099 entitled ‘Vacuum cleaner’ are examples of a vacuum cleaner having a cyclone dust collecting apparatus. The cyclone dust collecting apparatus comprises a cyclone body, which includes an air inlet and an air outlet. The cyclone body forms a whirling stream with contaminant-laden air drawn through the air inlet, into the cyclone body where particles are centrifugally separated from the drawn-in air. Cleaned air is discharged via the air outlet to the outside.
As is known, the airflow that exits from the air outlet is turbulent due to inertial forces of the whirling stream into the air outlet. The turbulent air current flowing through the air outlet hits the inside wall of the air outlet, or it collides with newly cleaned air flowing from the cyclone body such that air pressure and volume flowing through the air outlet can lost at the air outlet. The pressure loss at the air outlet increases the load on the vacuum source in a vacuum cleaner. Electrical power consumption therefore increases.
If the air outlet is smaller than the cyclone body in cross-section, the speed of cleaned air flowing from the air outlet will increase accordingly. Unfortunately, an air speed increase at the outlet will cause noise to increase such that noise abatement might be required.